1. Field of the Invention
The present invention relates to methods and apparatus for electrolytic disinfecting of objects in electrolyte containing solutions. More particularly, the present invention relates to methods and apparatus for electrolytic disinfection of such objects as contact lenses.
2. Description of the Prior Art
The general technique of purifying water or aqueous solutions of pathogens by subjecting the water or aqueous solution to a current in an electrolysis cell between at least one pair of electrodes is well known. In Stoner, U.S. Pat. No. 3,725,226, there is disclosed a technique in which water containing pathogenic microorganisms, such as bacteria, viruses, disease flukes, protozoa or the like, is subjected to an alternating potential applied across at least one pair of electrodes immersed in an aqueous solution, thereby passing each electrode through alternate cathodic and anodic phases. The peak voltage during the anodic phase is less than the voltage at which vigorous electrolytic oxygen is generated, and the peak voltage during the cathodic phase is greater than the voltage at which hydrogen is generated. By impressing an alternating current across the electrodes, not only are the pathogenic microorganisms in solution deactivated, but also the electrodes are defouled of deactivated micoorganisms which might accumulate on the electrodes during the anodic phase.
Shaffer, in U.S. Pat. No. 3,923,629, discloses an electrolytic technique for water purification in which a water solution to be purified is passed into a cell such that the fluid passes through permeable electrode layers in the cell. An alternating current having a current potential ranging from about 0.1 to about 20 volts and a frequency ranging from 0.1 to 10 cps is impressed across the electrodes in the cell so that as the fluid passes through the cell it passes through zones containing pairs of electrodes across which is impressed the alternating current.
Yet another prior art technique for purifying water is described by Teshima et al in U.S. Pat. No. 3,888,756. In this method water containing such contaminants as metallic ions, cyahides, silica, organic ions or the like, flows through an electrolytic cell. The cell is filled with a fluidized medium of particles of a conductive material such as graphite, and particles of a non-conductive material, such as glass balls, plastic balls or the like. As the impure water flows through the cell, a DC current is impressed across the electrodes. Each of the conductive particles in the fluidized bed functions as a small electrode in the bath thereby facilitating the removal of the impurities within the aqueous solution. While all of the above discussed techniques are effective for the removal and deactivation of contaminants in aqueous solutions, none is entirely effective for all objects immersed within the aqueous solutions in the electrolytic cells.
While electrolytic techniques for disinfection are known where water, or an electrolyte containing media is intended to be disinfected, problems have occurred when it was attempted to disinfect solid objects of irregular contours by the same technique. Theoretically, if a solid object were placed in an aqueous medium between two electrodes and subjected to an alternating potential as discussed in the above referenced Stoner patent, the object should be disinfected. In practice, however, it was found that where the object is of irregular contours, the object itself masks the current so that contaminated areas of aqueous medium in the shadows of the object will not be disinfected.
In the past, objects fabricated from non-conductive materials such as contact lenses, false teeth, beauty objects and the like, have been disinfected by either chemical treatment or by being subjected to hot water. However, for some objects such as soft contact lenses, heat accelerates the degradation of the lens material. Further, the use of chemical disinfecting agents for contact lenses is not permitted in some countries. Moreover, the conventional disinfection techniques have the disadvantages that considerable time is required to disinfect the object to be sterilized and in many instances hazardous chemicals must be used to disinfect various objects.
An electrolytic technique for disinfection of solid objects such as contact lenses, would be quite desirable to overcome the disadvantages of chemical or heat treatment that are now commonly used. However, electrolytic techniques are hindered by the requirement that small objects such as contact lenses must be held by larger objects such as lens containers which enhance the masking problem discussed above. If the chamber within the holding container is wired to the electrodes, when the container is opened, contamination on the outer walls of the container could get onto the fingers and subsequently onto the lenses when they are removed from the container. Thus, present FDA regulations require that any contact lens disinfection system must provide for disinfection of the total lens container as well as the lenses.
Brendlinger et al, U.S. Pat. No. 3,926,767, disclose an electrolytic treating apparatus designed for the pickling of metal strips of uniform dimensions. The continuous metal strip is fed into an elongated container which contains an aqueous electrolyte medium, preferably also containing an odd number of electrode pairs. As the metal strip passes through the container, it passes between the electrodes of each pair of electrodes and is subjected to electrolyzing treatment under extremely high currents which pickles the metal strip. In this system, the passage of current from one electrode to the metal strip via the intervening electrolyte solution and then from the metal strip through the intervening electrolyte solution to the other electrode is known as bipolar electrolyzing, which is a quite different process from disinfection.
A need, therefore, continues to exist for a method and apparatus by which various objects, particularly electrically non-conductive objects, can be rapidly and simply disinfected.